import {Mesh, ShaderMaterial, SphereBufferGeometry} from '../../build/three.module.js'

function LightProbeHelper(lightProbe, size) {
  this.lightProbe = lightProbe

  this.size = size

  var material = new ShaderMaterial({
    type: 'LightProbeHelperMaterial',

    uniforms: {
      sh: {value: this.lightProbe.sh.coefficients}, // by reference

      intensity: {value: this.lightProbe.intensity},
    },

    vertexShader: ['varying vec3 vNormal;', 'void main() {', '	vNormal = normalize( normalMatrix * normal );', '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );', '}'].join(
      '\n'
    ),

    fragmentShader: [
      '#define RECIPROCAL_PI 0.318309886',

      'vec3 inverseTransformDirection( in vec3 normal, in mat4 matrix ) {',

      '	// matrix is assumed to be orthogonal',

      '	return normalize( ( vec4( normal, 0.0 ) * matrix ).xyz );',

      '}',

      '// source: https://graphics.stanford.edu/papers/envmap/envmap.pdf',
      'vec3 shGetIrradianceAt( in vec3 normal, in vec3 shCoefficients[ 9 ] ) {',

      '	// normal is assumed to have unit length',

      '	float x = normal.x, y = normal.y, z = normal.z;',

      '	// band 0',
      '	vec3 result = shCoefficients[ 0 ] * 0.886227;',

      '	// band 1',
      '	result += shCoefficients[ 1 ] * 2.0 * 0.511664 * y;',
      '	result += shCoefficients[ 2 ] * 2.0 * 0.511664 * z;',
      '	result += shCoefficients[ 3 ] * 2.0 * 0.511664 * x;',

      '	// band 2',
      '	result += shCoefficients[ 4 ] * 2.0 * 0.429043 * x * y;',
      '	result += shCoefficients[ 5 ] * 2.0 * 0.429043 * y * z;',
      '	result += shCoefficients[ 6 ] * ( 0.743125 * z * z - 0.247708 );',
      '	result += shCoefficients[ 7 ] * 2.0 * 0.429043 * x * z;',
      '	result += shCoefficients[ 8 ] * 0.429043 * ( x * x - y * y );',

      '	return result;',

      '}',

      'uniform vec3 sh[ 9 ]; // sh coefficients',

      'uniform float intensity; // light probe intensity',

      'varying vec3 vNormal;',

      'void main() {',

      '	vec3 normal = normalize( vNormal );',

      '	vec3 worldNormal = inverseTransformDirection( normal, viewMatrix );',

      '	vec3 irradiance = shGetIrradianceAt( worldNormal, sh );',

      '	vec3 outgoingLight = RECIPROCAL_PI * irradiance * intensity;',

      '	gl_FragColor = linearToOutputTexel( vec4( outgoingLight, 1.0 ) );',

      '}',
    ].join('\n'),
  })

  var geometry = new SphereBufferGeometry(1, 32, 16)

  Mesh.call(this, geometry, material)

  this.type = 'LightProbeHelper'

  this.onBeforeRender()
}

LightProbeHelper.prototype = Object.create(Mesh.prototype)
LightProbeHelper.prototype.constructor = LightProbeHelper

LightProbeHelper.prototype.dispose = function () {
  this.geometry.dispose()
  this.material.dispose()
}

LightProbeHelper.prototype.onBeforeRender = function () {
  this.position.copy(this.lightProbe.position)

  this.scale.set(1, 1, 1).multiplyScalar(this.size)

  this.material.uniforms.intensity.value = this.lightProbe.intensity
}

export {LightProbeHelper}
